Chip conveyors are experiencing widespread use in many industrial applications. In shops and factories utilizing various metal working machines, such as grinders, lathes and drill presses, chip conveyors have proved particularly useful in moving scrap metal away from the machine and into a receptacle. Frequently, the scrap materials must be conveyed to an elevated location. U.S. Pat. Nos. 3,777,880, 3,828,920 and 4,130,195, all of which are assigned to the assignee of the present application, have been designed for conveying waste materials.
The aforesaid patents disclose what is commonly known as a push-bar or harpoon conveyor, typically comprising a long trough having a plurality of interconnected plows supported therein for reciprocal movement. A power source is arranged to effect reciprocal movement of the entire train of plows within the trough, whereby the waste materials are urged unidirectionally along the trough. A plurality of retaining members or barbs on the side walls of the trough oppose movement of the waste materials in the opposite direction.
The general shape of the plows is such that on a forward stroke they engage the conveyed material and advance it toward one end of the trough, but on a rearward stroke they tend to slide past the conveyed material so that it does not move rearwardly significantly with respect to the trough. The retaining members cooperate on the rearward stroke to further prevent the conveyed material from moving in a rearward direction within the trough.
A problem with the prior art conveyors is that they are typically more efficient for larger chips and metal turnings than for smaller ones. This has been found to be particularly true when the trough is inclined, because such chips and turnings are often too small to be effectively engaged by the material-retaining elements on the walls of the trough. Also, the force of gravity tends to encourage the smaller chips and turnings to slide downwardly in the trough on the rearward stroke of the plow train.
U.S. Pat. No. 4,052,311 discloses a second type of scrap conveyor having an inclined trough with a semicylindrical bottom, an elongated helical flight rotationally supported in the trough, and a drive mechanism mounted to the upper end of the trough for effecting rotation of the flight. As the helical flight rotates, solids such as chips and metal cuttings are carried upwardly in the trough by the rotating helix.
Although conveyors of the type disclosed in U.S. Pat. No. 4,052,311 have fulfilled their intended purposes, they have not proved satisfactory in all respects. First, although such conveyors satisfactorily convey small chips and cuttings, the helical flights often jam when certain objects or large cuttings and turnings get into the trough.
Second, the helical drive mechanism must normally cooperate with the upper end of the helix when small chips and turnings are conveyed, because the small chips and cuttings tend to foul the bearings or other drive train elements necessary to connect the drive mechanism with the lower end of the helix. When the drive mechanism is connected to the upper end of the helix, however, the introduction of foreign objects or large chips and cuttings at the lower end of the helix creates torques in the helix which distort its shape.
Accordingly, an object of this invention is to provide an improved conveyor apparatus for efficiently conveying both small and large cuttings and turnings upwardly along a trough from one location to a second location at a higher elevation.
Another object of this invention is to provide a conveyor apparatus, as aforesaid, having a configuration which minimizes the possibility of jams which stop or slow the movement of the waste through the conveyor.